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Questions tagged [nsexpression]

NSExpression is used to represent expressions in a predicate. Comparison operations in an NSPredicate are based on two expressions, as represented by instances of the NSExpression class. Expressions are created for constant values, key paths, and so on.

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NSExpression gives incorrect value

I have built a calculator based around NSExpression and I'm rather stumped as to why I'm receiving repeating decimals in a number of corner cases. I'm unable to cast the resulting value as an Int since the format of the NSExpression is entered by…
Hamer
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terminating with uncaught exception of type NSException in Swift 5

My code works when my code makes etc: 2 + 2 But my app shut down when my code makes ex: 2+2+ . I tried to do - catch code block and many error handling. I can't solve the problem. let islem: String = screenTextfield.text! let exp: NSExpression =…
Mustafa Çağrı Peker
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Aggregate Action with CoreData

I have a CoreData "data base" and to simplify let's say that my objects have two attributes: a variable name and a variable value. I want to aggregate the content of the DB by "variable name" ("GROUP BY") and for each of the variables "names" , I…
Mansour
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How to create a fetch to sum over the difference between attributes

In the entity Shift I have two attributes startTime and endTime, I want to take the difference and then sum over all fetched values. let fetchRequest = NSFetchRequest(entityName: "Shift") fetchRequest.predicate =…
Richard Legault
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How do I extract an Int value from NSExpression?

I have a map view(mapbox) with some cluster points, the cluster is arranged and displayed based on a geojson, the logic of the cluster as if it has neighbours they will cluster when the map is zoomed out. This works great, however, I need to…
nerway
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How do I fix error: Binary operator '==' cannot be applied to operands of type 'NSExpression.ExpressionType' and '_'

I am going through old code from HomeKit Catalog: Creating Homes, Pairing and Controlling Accessories, and Setting Up Triggers when I ran into an expression that says .KeyPathExpressionType I can't tell what the . in .KeyPathExpressionType is…
daniel
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Unable to create NSExpression with string from readLine()

This is my code: print("Please enter your formula:") let formula = readLine() if formula == ("[0-9+-*/%]"){ let result = NSExpression(format: formula) let result1 = result.expressionValue(with: nil, context: nil) as? Int …
tktkt
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Building predicate (NSExpression) to determine icon color for Mapbox SymbolStyle layer

I've recently started working with the Mapbox SDK on iOS and I've got some markers that I want to add to my map. Each marker represents an object that has several properties, among them: a type property (which backs to an enum) and a boolean…
bmt22033
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Deriving an expression using NSExpression

I am stuck at a piece of code where I need to get the expression result based on the passed dictionary. For example: expressionString = "(val1 + val2)" How it is possible to pass these values from an dictionary or somewhere else. I searched many…
Anupam Gupta
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Swift - use of unresolved identifier NSExpression

I tried the below code on https://iswift.org/playground, but it says use of unresolved identifier NSExpression. Please let me know if I am missing something. var numericExpression = "4 + 3 - 2" let expression = NSExpression(format:…
Gunjan Goel
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String format parameters binding dictionary

Is there any built-in solution that allows to substitute strings in a manner of NSExpression does (i.e. with a binding dictionary provided)? So instead of: let s = String(format: "%@ %@", arguments: ["foo", "bar"]) // "foo bar" we have: let s =…
m8labs
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Swift 4 NSExpression with Multiple Functions

So I have a string formula that let's say is: let testValue = 10 let formula = "(max(testValue - 20,0) * 14) + testValue - max(testValue - 20,0)" I can do simple arithmetic, multiplication, division, subtracts, ect but how would I combine the Max…
Torewin
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Create a new NSExpression

How can i create a NSExpression with a constant value for using with the PredicateEditor. for Example: the leftExpression should be a string "state", the rightExpression should be as string "Germany" i've tried: NSExpression left = new…
Klaus Grosche
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Swift NSExpression error handling

I was wondering if there was a way to catch the NSInvalidArgument error that is thrown when a NSExpression is invalid; such as: “4+”. I have trying doing a guard, if let, but both seem to fail and the exception is still thrown. I know that there…
Torewin
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Swift 3 Core Data - NSExpression combine multiple functions

I need this expression --> sum:(abs:(amount) * -1) and my code is: let absExpression = NSExpression(forFunction: "abs:", arguments: [NSExpression(forKeyPath: Table.COLUMN_AMOUNT)]) let minusAbsExpression = NSExpression(format: "%@ * -1",…
Farzad Rohani
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